Pyridyloxy-phenoxy-alkanoic acid esters and derivatives

ABSTRACT

This invention relates to 3-alkoxy-4-substituted-phenoxy-2,3-unsaturated acid esters, derivatives thereof, and the use of said acid esters and derivatives for the control of weeds.

This is a continuation-in-part of Ser. No. 361,161, filed Mar. 23, 1982, which is a continuation-in-part of Ser. No. 341,736, filed Jan. 22, 1982, now U.S. Pat. No. 4,429,167, which is a continuation-in-part of Ser. No. 299,413, filed Sept. 4, 1981, now U.S. Pat. No. 4,408,076, is a continuation-in-part of Ser. No. 270,938, filed June 5, 1981, now abandoned, which is a continuation-in-part of Ser. No. 196,795, filed Oct. 14, 1980, now abandoned, the entire disclosures of which are incorporated herein by reference.

The novel 3-alkoxy-4-substituted-phenoxy-2,3-unsaturated acids, esters and derivatives thereof of the present invention are represented by the following formulas A', B', C', and D': ##STR1## wherein, R is ##STR2## W is O, S, NH or CH₂ ; each of X and Y is independently selected from hydrogen, bromo, chloro, fluoro, lower alkyl, lower alkoxy, lower alkoxycarbonyl, nitro, cyano, trifluoromethyl, chlorodifluoromethyl, fluoromethyl, chloromethyl, and difluoromethoxy;

n is 1 or 2;

each of X' and X" is independently selected from hydrogen, fluoro, chloro, bromo, iodo, trifluoromethyl, methoxy or nitro, provided that both X' and X" cannot be trifluoromethyl, methoxy or nitro;

R¹ is hydrogen or lower alkyl;

R² is lower alkyl;

Q is ##STR3## --CH₂ --X³ or --CH₂ --OR⁶ in which, R³ is hydrogen, lower alkyl, lower haloalkyl, lower cyanoalkyl, lower alkenyl, lower haloalkenyl, lower alkynyl, lower alkoxyalkyl, lower dialkylaminoalkyl, lower alkylthioalkyl, lower alkylsulfinyalkyl, lower alkylsulfonylalkyl, tetrahydrofuranylmethyl, tetrahydropyranylmethyl, benzyl, halobenzyl, lower alkylbenzyl, lower alkoxybenzyl, phenyl, halophenyl, lower alkoxyphenyl, lower alkylphenyl, cycloalkyl, cycloalkalkyl, N-alkylideneamino, sodium, potassium, magnesium or calcium;

each of R⁴ and R⁵ is independently selected from hydrogen, lower alkyl, lower hydroxyalkyl, lower alkoxyalkyl or lower alkysulfonyl;

X³ is bromo, chloro, fluoro or iodo; and

R⁶ is hydrogen or acyl.

In the description and claims hereinafter, each of R-R⁶, n, Q, W, X, X', X", X³ and Y is as defined above, unless otherwise specified.

The compounds of formula (A') wherein Q is ##STR4## can be produced by the reaction of a phenol of formula (I) ##STR5## with a 4-halo compound of formula (II) in the presence of a base such as alkali metal hydroxide or alkali metal carbonate. The reaction is generally conducted at about room temperature to reflux temperature in an organic solvent such as dimethylformamide (DMF), acetone, tetrahydrofuran (THF), dimethylacetamide (DMA), dimethylsufoxide (DMSO), or the like using about equimolar amounts of base, a phenol of formula (I) and a 4-halo compound of formula (II). X² represents bromo, chloro or iodo.

The thio compounds of formula (A') can be prepared starting with an acid of formula (A') which is converted into the acid halide and then reacted with a mercaptan. Alternatively, a phenol of formula (I) is reacted with a 4-halo thiolester of the general formula (II) above in the presence of base.

An amide of formula (A') can be prepared by the reaction of an acid halide of an acid of formula (A') with the appropriate amine.

An alcohol of formula (A') wherein Q is --CH₂ --OR⁶ can be prepared by reduction of an acid or ester of formula (A') using, for example, lithium borohydride or lithium aluminumhydride in ether or THF at a low temperature. Esters of an alcohol of formula (A') can be prepared by the reaction of an acyl halide or acyl anhydride in pyridine at about room temperature or lower.

A halide of the present invention of formula (A') wherein Q is --CH₂ -- X³ can be prepared by reaction of an alcohol of formula (A') wherein Q is --CH₂ --OH with phosphorus tribromide, phosphorus trichloride, or triphenylphosphine dihalide in acetonitrile. In another embodiment of the present invention, there is provided 3-oxo derivatives of formula (B') which can be derived from the novel compounds of formula (A'). The compounds of formula (B') are useful for the control of weeds. ##STR6##

A compound of formula (B') can be prepared by the reaction of a 3-alkoxy compound of formula (A') such as a 3-methoxy compounds of formula (A') with an acid such as dilute perchloric acid or acetic acid in an organic solvent such as methylenedichloride, tetrachloride or THF. The reaction is usually conducted at about room temperature or lower.

In another embodiment of the present invention, there is provided compounds of formula (C') which can be prepared by selective reduction of a compound of formula (B') using sodium borohydride in alcohol at low temperature. ##STR7## The alcohols of formula (C') and carboxylic esters thereof are useful for the control of weeds.

In another embodiment of the present invention, there is provided compounds of formula (D') which are useful for the control of weeds. ##STR8##

The compounds of formula (D') can be prepared by treating an alcohol of formula wherein Q is --CH₂ --OH with perchloric acid.

Carboxylic esters of formula (B') wherein Q is ##STR9## can be prepared by the following outlined method also: ##STR10##

The following terms have the meaning indicated as used herein and the appended claims.

The term "lower alkyl" refers to an alkyl group of one to six carbon atoms.

The term "lower alkoxy" refers to an alkoxy group of one to six carbon atoms.

The term "lower alkoxycarbonyl" refers to an alkoxycarbonyl group of two to six carbon atoms.

The term "acyl" refers to a carboxylic acyl group such as lower aliphatic acyl group of one to six carbon atoms or aryl acyl group of six to twelve carbon atoms. Typical acyl groups include acetyl, benzoyl, p-chlorobenzoyl, and the like.

The term "lower alkenyl" refers to an alkenyl group of two to six carbon atoms with mono-unsaturation such as allyl and n-but-2-enyl.

The term "lower alkynyl" refers to an alkynyl group of two to six carbon atoms with monounsaturation such as propargyl.

The term "cycloalkyl" refers to a cycloalkyl group of three to six carbon atoms.

The term "cycloalkyl" refers to a cycloalkalkyl group of four to seven carbon atoms.

The term "halo" refers to a bromo, chloro or fluoro group.

The compounds of formula A', B', C', D' are useful for the control of weeds using pre- and/or post-emergent treatments. The compounds can be applied in the form of dusts, granules, solutions, emulsions, wettable powders and suspentions. Application of a compound of the present invention is made according to conventional procedure using from about one-half or less to ten pounds per acre. The application of a compound of the present invention to the "locus" of the weeds includes application to the seeds, the plant (weed) or parts of the plant, or the soil. Methods of preparing herbicidal formulations which can be used with a compound of the present invention are described in the literature along with suitable liquid and solid carrier materials such as in U.S. Pat. Nos. 4,192,669 and 4,163,661 which are incorporated herein by reference. While some of the compounds of the present invention have activity on broad leaf plants, the compounds, in general, demonstrate a higher level of herbicidal activity on the grass weeds. The optimum usage of a compound of the present invention is readily determinable by one of ordinary skill in the art using routine testing such as greenhouse testing and small plot testing.

The term "herbicide", as used herein, refers to an active ingredient which modifies the growth of plants because of phytotoxic or plant growth regulating properties so as to retard the growth of the plant or damage the plant sufficiently to kill it.

The compounds of the present invention demonstrate selective activity as herbicides against grass weeds. Crops such as cotton, sugar beet, soybeans and squash show excellent tolerance. The compounds of the present invention, in general, show higher level of herbicidal activity when the postemergent method of application is used. Grass plant (weed) species on which the compounds of the present invention show effective herbicidal activity include shattercane, crabgrass, sprangle-top, wild oats, bermudagrass, tall fescue, rice, wheat, barley, corn, blue panicum, foxtails, rough bluegrass, winter rye, annual ryegrass, watergrass and Johnsongrass. It appears to be most effective to apply the active compound prior to the heading stage of the grass weed.

The compounds of the present invention, in view of their broadspectrum grass weed herbicidal activity, can be advantageously combined with broadleaf weed herbicides for broadspectrum postemergence weed control in most broadleaf crops. Examples of herbicides which can be combined with a compound of the present invention include glyphosate, bentazone, diuron, paraquat, 2,4-D, 2,4-DB, diquat, endothal, dinoseb, dicamba, norflurazon, nitrofen, cyanozine, methazole, mefluidide, metribuzin, cycloate, fluometuron, linuron, dalapon, bifenox and alachlor for controlling a broad spectrum of weeds.

The compounds of the present invention are useful for application to sugarcane in order to increase the sucrose content of the sugarcane.

The compounds of the present invention include the isomeric forms and mixtures thereof. Thus, the invention includes the optically active isomers and racemic mixtures. Unless otherwise specified herein, the compounds described in the examples are racemic mixtures.

The following examples are provided to illustrate the practice of the present invention. Temperature is given in degrees centigrade. All parts are by weight unless otherwise indicated. RT means room temperature.

EXAMPLE 1

A mixture of 4-(2-chloro-4-trifluoromethylphenoxy)phenol (1.16 g), ethyl 4-bromo-3-methoxy-2-pentenoate (1.74 g) and potassium carbonate (0.73 g) in DMF (5 ml.) is heated to about 130° for 2 hours. Thereafter, DMF is removed. The residue is filtered and washed with methylene dichloride. The filtrate is washed, dried and evaporated to dryness. The oily residue is subjected to prep. thin layer chromatography using 20% ethylacetate/hexane to yield the ethyl ester of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoic acid, MS m/e 444 (M⁺).

EXAMPLE 2

A mixture of 4-(2-chloro-4-trifluoromethylphenoxy)phenol (6.9 mmol.), methyl 4-bromo-3-methoxy-2-pentenoate (8.9 mmol.) and potassium carbonate (1.5 equis.) in acetone (15 ml.) is refluxed for 48 hours. After filtration, the filtrate was concentrated and the residue chromatographed on silia gel using 20% ethylacetate/hexane to give the methyl ester of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoic acid.

Some compounds of formula A' which are prepared according to the procedure of the foregoing examples are as follows (Table I and II).

                  TABLE I                                                          ______________________________________                                          ##STR11##                                                                     X         Y          R.sup.1  R.sup.2                                                                               R.sup.3                                   ______________________________________                                         H         CF.sub.3   Me       Me     Me                                        H         CF.sub.3   Et       Me     Me                                        Cl        CF.sub.3   Et       Me     Me                                        Cl        CF.sub.3   Me       Et     Me                                        H         OCF.sub.3  Me       Me     Me                                        Cl        OCF.sub.3  Me       Me     Me                                        Cl        Cl         Me       Me     Et                                        NO.sub.2  CF.sub.3   Me       Me     Me                                        H         Br         Me       Me     Et                                        Me        OMe        Me       Me     Me                                        ______________________________________                                    

                  TABLE II                                                         ______________________________________                                          ##STR12##                                                                     X         Y          R.sup.1  R.sup.2                                                                               R.sup.3                                   ______________________________________                                         Cl        Cl         Me       Me     Me                                        H         CF.sub.3   Me       Me     Me                                        Cl        CF.sub.3   Me       Me     Me                                        H         CHF.sub.2  Me       Me     Me                                        H         CClF.sub.2 Me       Me     Me                                        Me        CF.sub.3   Et       Me     Et                                        F         CF.sub.3   Me       Me     Me                                        H         Br         Me       Me     Me                                        Cl        Cl         Me       Et     Et                                        Cl        Cl         Et       Et     Et                                        ______________________________________                                    

EXAMPLE 3

A mixture of the methyl ester of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoic acid (0.5 g), 35% aqueous perchloric acid (5 ml.) and methylene dichloride (5 ml.) is stirred at RT for 4 days. Then the solution is extracted with methylene dichloride. The combined extracts are washed, dried and evaporated. The residue is purified by prep. thin layer chromatography using 20% ethyl acetate/hexane to yield methyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate.

The product of Example 1 is treated with aqueous perchloric acid as above to yield ethyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate, MS m/e 430 (M⁺).

By use of the foregoing procedure, each of the compounds of Tables I and II are converted into the corresponding 3-oxo-compound of formula (B") such as methyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate, methyl 4-[4-(4-trifluoromethoxy-phenoxy)phenoxy]-3-oxopentanoate, ethyl 4-[4-(2,4-dichlorophenoxy)phenoxy]-3-oxopentanoate, MS m/e 396 (M⁺), methyl 4-[4-(4-dichlorophenoxy)phenoxy]-3-oxopentanoate, methyl 4-[4-(3,5-dichloropyridyloxy)phenoxy]-3-oxopentanoate and methyl 4-[4-(5-trifluoromethylpyridyloxy)phenoxy]-3-oxopentanoate.

EXAMPLE 4

A mixture of 4-(2-nitro-4-trifluoromethylphenoxy)phenol (9.36 mm)., ethyl 4-bromo-3-methoxy-2-pentenoate (12 mm.) and K₂ CO₃ (14 mm.) in acetone (20 ml.) is refluxed for 24 hours. After filtration, the filtrate is concentrated and the oily residue chromatographed on silica gel to yield ethyl 4-[4-(2-nitro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoate.

A solution of the above ethyl ester in 35% perchloric acid and water is stirred at RT for 3 days and then worked up to give ethyl 4-[4-(2-nitro-4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate.

EXAMPLE 5

To a mixture of lithium aluminum hydride (200 mg) and anhydrous ether (5 ml.) is added dropwise at 0°, a mixture of ethyl 4[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoate (400 mg) and ether (5 ml.). After addition is complete, the mixture is stirred for about minutes. Wet ether and water is added to destroy excess hydride. Filtration and evaporation of filtrate gives 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-penten-1-ol.

EXAMPLE 6

A mixture of ethyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoate (10 mmol), ethanol (20 ml.) and 1N Na OH (20 ml.) is prepared and then heated at reflux for a few hours to complete the reaction. Removal of solvent gives the sodium salt of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoic acid. The free acid is obtained by acidification of the salt using dilute H₂ SO₄, and extraction with methylene dichloride and evaporation. Other acid salts can be prepared by titrating the free acid with an organic solution of the base, e.g., methanolic solution of potassium methoxide and the like.

EXAMPLE 7

Thionyl chloride (20 ml.) is added to 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoic acid (10 mm.) in anhydrous ether (10 ml.). The mixture is refluxed for a few hours. Then, ether and excess thionyl chloride is removed by vacuum to yield 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoyl chloride.

EXAMPLE 8

To a mixture of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoyl chloride (10 mm.) and ether (10 ml.) is added methyl mercaptan (12 mm.) and pyridine (1 ml.) at about -20°. The mixture is stirred for about 30 minutes and then allowed to rise to about 0° and stand for about 2 hours. The mixture is then diluted with ether and water and the ether phase separated, washed, dried and solvent removed to give the methylthiol ester of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoic acid.

EXAMPLE 9

A mixture of 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoyl chloride (15 mm) and THF (15 ml.), at 0°, is prepared and then slight excess of methylamine introduced. The reaction mixture is allowed to stand under nitrogen for about one hour. Then the reaction is allowed to rise to RT and solvent removed. The residue is taken up in methylene dichloride, washed, dried and solvent removed under vacuum to yield N-methyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenamide.

EXAMPLE 10

A mixture of ethyl 3-oxopentanoate (20 g) and trimethylformate (5 eq., 94 ml.) in the presence of 6 g of Amberlyst-15 (trademark of Rohm & Haas Corp.) is stirred at RT overnight. After filtration, the filtrate is concentrated and then distilled to give ethyl 3-methoxy-2-pentenoate (19.5 g).

A mixture of the above ethyl ester, N-bromosuccinimide (26.3 g), benzoyl peroxide (0.3 g.) and carbon tetrachloride (100 ml.) is heated to reflux and irradiated with 150 watt flood lamp until substantially clear solution is obtained. Thereafter, the reaction is filtered and the filtrate then concentrated and distilled (78°/2 mm) to give ethyl 4-bromo-3-methoxy-2-pentenoate.

EXAMPLE 11

(A) Following the procedure of Example 1, 4-(2-nitro-4-trifluoromethylphenylamino)phenol is reacted with ethyl 4-bromo-3-methoxy-2-pentenoate to give ethyl 4-[4-(2-nitro-4-trifluoromethylphenylamino)phenoxy]-3-methoxy-2-pentenoate

(B) Following the procedure of Example 3, the product of part (A) is treated with aqueous perchloric acid to give ethyl 4-[4-(2-nitro-4-trifluoromethylphenylamino)phenoxyl]-3 oxopentanoate, MS m/e 512 (M⁺).

In the same way, there is prepared methyl 4-[4-(2-nitro-4-chlorophenylamino)phenoxy]-3-methoxy-2-pentenoate and methyl 4-[4-(2-nitro-4-chlorophenylamino)phenoxy]-3-oxopentanoate starting with 4-(4-chloro-2-nitrophenylamino)phenol and methyl 4-bromo-3-methoxy-2-pentenoate.

EXAMPLE 12

A spray solution of water/acetone (1:1) and surfactant (1%) was prepared containing (1) the compound of Example 1 (Compound 1) and (2) the second compound of Example 3 (Compound 2) and sprayed (equivalent to 10 lb/acre) on seedlings of foxtail (Setaria viridis) and watergrass (Echinochlou crusgalli). Observation two weeks after spraying Compound 1 and 2 showed 100% herbicidal activity for each of test Compounds 1 and 2. Testing of Compounds 1 and 2 showed no injury to soybeans at 10 lb/acre.

Pre-emergent herbicidal activity of Compound 2 was tested on foxtail, watergrass, shattercane, and wild oats. The average activity was 86% for the four species.

EXAMPLE 13

To a slurry of LiAIH₄ (100 mg) in anhydrous ether (20 ml) is added dropwise at 0°, a solution of ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoate (500 mg) in ether. After addition is complete, the reaction mixture is stirred for about 20 minutes. Excess of the hydride is decomposed using wet ether and water. Filtration and evaporation of filtrate gives the C-1 alcohol, 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-penten-1-ol, MS m/e 440 (M⁺).

EXAMPLE 14

To a slurry of LiAlH₄ (200 mg) in anhydrous ether (15 ml) is added at 0° a solution of ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate (400 mg) in ether (5 ml). After addition is complete, the reaction mixture is stirred at RT for about one hour. Excess of the hydride is decomposed using wet ether and water, the mixture is filtered and filtrate concentrated. The oily product is purified by prep. thin layer chromatography to give 4-[4-(4-trifluoromethylphenoxy)phenoxy]-pentane-1,3-diol, MS m/e 500 (M⁺).

EXAMPLE 15

To a solution of ethyl 4-[4-(2-nitro-4-chlorophenoxy)phenoxyy]-3-oxopentanoate (600 mg) in absolute ethanol (10 ml) is added at 0°, NaBH₄ (300 mg). After addition is complete, the reaction mixture is stirred for about 20 minutes. Then the solution is taken up in CH₂ Cl₂, washed with brine, dried and evaporated to give ethyl 4-[4-(2-nitro-4-chlorophenoxy)phenoxy]-3-hydroxypentanoate.

EXAMPLE 16

To a slurry of LiAlH₄ (400 mg) in anhydrous ether (20 ml) is added dropwise at 0°, a solution of ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoate (1.2 g) in ether (10 ml). After addition is complete, the reaction mixture is stirred for about 10 minutes. Excess hydride is decomposed with wet ether and water. After filtration, the filtrate is concentrated to give the alcohol, 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-penten-1-ol.

The alcohol (600 mg) is stirred with 5 ml of 35% HClO₄ in CH₂ Cl₂ (5 ml) for about 20 minutes. The solution is then extracted with CH₂ Cl₂ followed by washing, drying and evaporation. The product is then purified by prep. thin layer chromatography to give 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-oxo-1-pentene, MS m/e 336 (M⁺).

EXAMPLE 17

To a solution of ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate (450 mg) in ethanol (5 ml) is added NaBH₄ (150 mg) at 0°. The resulting mixture is then stirred at 0° for about 10 minutes. The mixture is diluted with CH₂ Cl₂, washed with saturated NaCl solution, dried and evaporated to dryness to give ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-hydroxypentanoate, in quantitative yield, MS m/e 398 (M⁺).

EXAMPLE 18

The process of Example 17 is repeated using ethyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate (400 mg) and NaBH₄ (100 mg) to give ethyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-hydroxypentanoate, MS m/e 432 (M⁺).

EXAMPLE 19

To a slurry solution of LiAlH₄ (200 mg) in anhydrous ether (5 ml) is added dropwise at 0°, a solution of ethyl 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-pentenoate (400 mg) in anhydrous ether (5 ml). After addition is complete, the reaction mixture is stirred at 0° for about 10 minutes. Excess hydride is decomposed with wet ether and water. The mixture is filtered and filtrate washed, dried and evaporated to give 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-methoxy-2-penten-1-ol.

The foregoing alcohol (380 mg) is reacted with 35% HClO₄ (4 ml) in CH₂ Cl₂ (4 ml) at RT for 24 hours. The mixture is then extracted with CH₂ Cl₂ and the combined extracts washed, dried and concentrated to dryness. The product is purified by prep. thin layer chromatography to give 4-[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]-3-oxo-1-pentene, MS m/e 396 (M⁺).

EXAMPLE 20

A solution of 2-[4-(4-trifluoromethylphenoxy)phenoxy]propionyl chloride (1.5 g) and methylene chloride (5 ml) is added dropwise at 0° to a solution of 2,2-dimethyl-1,3-dioxane-4,6-dione (680 mg) in methylene chloride (20 ml) containing pyridine (0.7 ml). The resulting mixture is stirred at RT for 2 hours. The reaction mixture is then poured into water, acidified with dilute HCl and extracted with methylene chloride. The combined extracts are washed with brine, dried and evaporated to give 2-[4-(4-trifluoromethylphenoxy)phenoxy]-propionyl meldrum acid, an oil.

The above meldrum acid is treated with n-butanol (20 ml) at 120° for about 4 hours. After aqueous workup, the oily concentrate is purified by prep. thin layer chromatography on silica gel to give n-butyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate, MS m/e 424 (M⁺).

EXAMPLE 21

A mixture of 2-nitro-3-trifluoromethyl-4'-hydroxydiphenylamine (1 g), ethyl 4-bromo-3-methoxy-2-pentenoate (990 mg) and potassium carbonate (694 mg) in acetone (10 ml) is refluxed for 24 hours. After filtration and concentration, the crude product is purified by prep. thin layer chromatography on silica gel to give ethyl 4-[4-(2-nitro-4-trifluoromethylanilino)phenoxy]-3-methoxy-2-pentenoate which is treated with 35% HClO₄ in methylene chloride to give ethyl 4-[4-(2-nitro4-trifluoromethylanilino)phenoxy]-3-oxopentanoate, MS m/e 440 (M⁺).

EXAMPLE 22

Post-emergence activity on the grasses (GR) greenfoxtail, watergrass, shattercane and wild oats was tested for the compound of Examples 13, 14, 17, 18, 20 and 21 (compounds No. 3, 4, 5, 6, 7 and 8, respectively) and on the broadleafs (BL) annual morningglory, sesboria, soybean and velvet leaf by spraying at a rate equivalent to 10 lb/acre. The average score is given in percent control.

    ______________________________________                                         Compound No.       GR     BL                                                   ______________________________________                                         3                  100    14                                                   4                   96    8                                                    5                  100    11                                                   6                  100    3                                                    7                  100    7                                                    8                  100    0                                                    ______________________________________                                    

EXAMPLE 23

An emulsifiable concentrate was prepared having the following composition (components in percent by weight).

    ______________________________________                                         (VI)       Compound B  27.78                                                              Igepol CO-530                                                                              2.67                                                               Tween 21    2.67                                                               Tween 81    2.67                                                               Corn oil    64.21                                                   ______________________________________                                    

Compound B is ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-oxopentanoate (90% purity). Tween 21 is non-ionic surfactant, polyoxyethylene sorbitan monolaurate and Tween 81 is polyoxyethylene sorbitan monooleate. Tween is a trademark of ICI Americas. Igepal CO-530 is a non-ionic surfactant [nonylphenoxypoly(ethleneoxy)ethanol] of GAF, Inc.

    ______________________________________                                         (VII)      Compound C   29.3                                                              Toximol S    6.4                                                               Atlox 8916 TF                                                                               1.6                                                               Tenneco 500-100                                                                             62.7                                                   ______________________________________                                    

Compound C is ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-hydroxypentanoate (90% purity).

A spray solution was prepared using 30 parts of concentrate VII, 950 parts of water and 28 parts of non-phytotoxic crop oil and applied to young Johnson grass at the rate of 1.0 lb. per acre. The test plots were observed after two weeks. The application gave 100% control of the Johnson grass.

    ______________________________________                                         (VIII)     Compound B   27.8                                                              Toximol R    3.0                                                               Toximol S    9.0                                                               Tenneco 500-100                                                                             60.2                                                   ______________________________________                                    

Concentrate VIII was diluted in water and applied at the rate of 2.0 lb. per acre to test specimens, in a greenhouse, of watergrass, green foxtail, shattercane, blue panicum, tallfescue, sprangletop, annual ryegrass, downy brome, wild oats, crabgrass, milo, corn, probred wheat and barley. The average herbicidal activity of two or more evaluations of each of the foregoing grass species was 80% or greater.

Toximol R and S are surfactants of the Stepan Chemical Corporation, Ill. Atlox 8916F in a surfactant of ICI Americas, Del. Tenneco 500-100 is an aromatic solvent of the Tenneco Corporation.

EXAMPLE 24

Flowable formulations were prepared having the following compositions, percent by weight.

    ______________________________________                                         (XI)        (A)    Compound B  3.00                                                               Toximol 360A                                                                               3.00                                                               Sun 7N (oil)                                                                               30.00                                                       (B)    Water       60.85                                                              Gelvatol 20/30                                                                             3.00                                                               Kelzan      0.15                                            ______________________________________                                    

Premix (A) was dispersed in high speed blender for about one minute and then Premix (B) was poured into Premix (A) while stirring at high speed. After addition of Premix (B) stirring was continued about 5 minutes.

    ______________________________________                                         (X)         (A)    Compound C  3.00                                                               Toximol 360A                                                                               3.00                                                               Sun 7N      30.00                                                       (B)    Water       60.85                                                              Gelvatol 20/30                                                                             3.00                                                               Darvan No. 1                                                                               0.15                                            ______________________________________                                    

Premix (A) and (B) were combined as described for flowable IX above. Concentration of active ingredient 2.7%.

Sun 7N is a non-phytotoxic oil of the Sun Chemical Company. Gelvatol 20/30 is a polyvinyl alcohol, molecular weight about 10,000 of the Monsanto Company. Kelzan is a thickener agent (xanthum gum). Darvan No. 1 is a dispersant of the RT Vanderbilt Company.

EXAMPLE 25

The compound, 2-[4-(4-trifluoromethylphenoxy)-phenoxy]propionyl meldrum acid (V; W is oxygen, R is 4-trifluoromethylphenyl, and R¹ is methyl) is reacted with the alcohol R³ --OH using the procedure of Example 20 to prepare the respective ester under Table III.

                  TABLE III                                                        ______________________________________                                          ##STR13##                                                                             R.sup.3                                                                ______________________________________                                                 CH.sub.2CN                                                                     CH.sub.2CHCH.sub.2                                                             CH.sub.2CHCCl.sub.2                                                            CH.sub.2CCH                                                                    CH.sub.2CH.sub.2OCH.sub.3                                                       ##STR14##                                                                     CH.sub.2CH.sub.2Cl                                                              ##STR15##                                                                     CH.sub.2CH.sub.2SCH.sub.2CH.sub.3                                               ##STR16##                                                                      ##STR17##                                                                      ##STR18##                                                                      ##STR19##                                                                      ##STR20##                                                                      ##STR21##                                                                      ##STR22##                                                                      ##STR23##                                                             ______________________________________                                    

EXAMPLE 26

Following the procedure of Example 17, each of the 3-oxo esters under Table III is reduced using sodium borohydride to yield the respective 3-hydroxy esters of the following formula: ##STR24##

EXAMPLE 27

Ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-hydroxypentanoate is reacted with 1.1 equivalent of acetyl chloride and 1.0 equivalent of pyridine in benzene to yield ethyl 4-[4-(4-trifluoromethylphenoxy)phenoxy]-3-acetoxypentanoate. Similarly, using n-propanoyl chloride and isopropanoyl chloride yield the respective 3-n-propanoate and 3-isopropanoate.

Carbonates of the 3-hydroxy compounds of formula C' are prepared using the above procedure and 1.1 equivalents of, for example, ethyl chloroformate or methyl chloroformate. The 3-carbonates are useful herbicides for grass weeds also.

In the preparation of the 3-hydroxy compounds of formula C', in addition to reduction of the respective 3-oxo compound of formula B', the 3-hydroxy compounds such as the esters can be prepared by the following outlined method. ##STR25##

EXAMPLE 28

Each of the compounds, methyl 4-[4-(3,5-dichloropyridyloxy)phenoxy]-3-oxopentanoate and methyl 4-[4-(5-trifluoromethylpyridyloxy)phenoxy]-3-oxopentanoate is reacted with NaBH₄ by the procedure of Example 17 to yield methyl 4-[4-(3,5-dichloropyridyloxy)phenoxy]-3-hydroxypentanoate and methyl 4-[4-(5-trifluoromethylpyridyloxy)phenoxy]-3-hydroxypentanoate, respectively.

EXAMPLE 29

The process of Example 20 is repeated with the exception of using 2-[4-(6-chloro-2-quinolinyloxy)phenoxy]-propionyl chloride as the starting material in place of 2-[-(4-trifluoromethylphenoxy)phenoxy]-propionyl chloride to yield as the final product, n-butyl 4-[4-(6-chloro-2-quinolinyloxy)phenoxy]-3-oxopentanoate.

By using 2-[4-(6-fluoro-2-quinolinyloxy)phenoxy]-propionyl chloride as the starting material and ethyl alcohol in place of n-butyl alcohol in the process of Example 20, there is obtained ethyl 4-[4-(6-fluoro-2-quinlinyloxy)phenoxy]-3-oxopentanoate which is reduced using NaBH₄ in alcohol to yield ethyl 4-[4-(6-fluoro-2-quinolinyloxy)phenoxy]-3-hydroxypentanoate.

EXAMPLE 30

The compound, 6-fluoro-2-(4-hydroxyphenoxy)quinoxaline, is used as the starting material in Example 1 in place of 4-(2-chloro-4-trifluoromethylphenoxy)phenol to yield ethyl 4-[4-(6-fluoro-2-quinoxalyloxy)phenoxy]-3-methoxy-2-pentenoate which is reacted with aqueous perchloric acid by the process of Example 3 to yield ethyl 4-[4-(6-fluoro-2-quinoxalyloxy)phenoxy]-3-oxopentanoate. The 3-oxo ester on reduction with NaBH₄ yield the 3-hydroxy ester, ethyl 4-[4-(6-fluoro-2-quinoxalyloxy)phenoxy]-3-hydroxypentanoate.

EXAMPLE 31

To a suspension of 2-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]propionyl chloride (1.38 mmol) in 5 ml. of methylene chloride, under nitrogen, at 0°, is added 2,2-dimethyl-1,3-dioxane-4,6-dione (198 mg, 1.38 mmol) followed by pyridine (0.5 ml). The resulting mixture is stirred at 0° for 1.5 hour and at RT for 1 hour. The reaction mixture is poured into 2% HCl and methylene chloride. The organic phase is separated, washed with brine (2X) and dried to give 2-[4-(5-trifluoromethyl-2-pyridyloxy)-phenoxy]propionyl meldrum acid, a red solid.

The above meldrum acid is heated in ethanol (30 ml) to reflux for 2 hours. The reaction mixture is stored at RT overnight. Ethanol is removed by retoevaporation, and the resulting oily residue is purified by prep. thin layer chromatography (silica gel, 15% ethyl acetate/hexane) to give ethyl 4-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-oxopentanoate.

nmr (CDCl₃) δ 1.22 (t, 3, 7 Hz, CH₃ CH₂ O--), 1.52 (d, 3, 7 Hz, CH₃ CH), 3.63 (s, 2, --C(O)CH₂ C(O)--), 4.12 (q, 2, 7 Hz, --OCH₂ CH₃), 4.72 (q, 1, 7 Hz, CHCH₃), 7.38 (d of d, 1, 9 Hz, 2 Hz, pyridyl 4-H) and 8.38 ppm (br s, 1, pyridyl 6-H).

EXAMPLE 32

To a solution of ethyl 4-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-oxopentanoate (175 mg, 0.44 mmol) in 5 ml of absolute ethanol at 0° is added sodium borohydride (32 mg, 0.84 mmol). The mixture is stirred for 15 minutes, after which it is poured into water and methylene chloride. The aqueous phase is separated and back-extracted with methylene chloride. The combined solvent extracts are washed with brine and dried. Solvent is removed by rotoevaporation, and the residue is purified by prep. thin layer chromatography (silica gel, 25% ethyl acetate/hexane) to yield ethyl 4-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-hydroxypentanoate.

nmr (CDCl₃) δ 1.25 (t, 3, 7 Hz, CH₃ CH₂ O--), 1.33 (d, 3, 6 Hz, CH₃ CH), 2.62 (d, 2, 6 Hz, CH₂ COO--), 4.13 (q, 2, 7 Hz, CH₃ CH₂ O--), 7.77 (d of d, 1, 2 Hz, 9 Hz, pyridyl 4-H) and 8.37 ppm (br s, 1, pyridyl 6-H).

EXAMPLE 33

Following the procedure of Example 31 to 2-[4-(6-fluoro-2-quinoxalyloxy)phenoxy]-propionyl chloride in 10 ml of methylene chloride is added 2,2-dimethyl-1,3-dioxane-4,6-dione (333 mg, 1.15 eq.) and pyridine (0.32 ml, 2 eq.) to give 2-[4-(6-fluoro-2-quinoxalyloxy)phenoxy]propionyl meldrum acid, which is then heated in methanol (40 ml) to reflux for about 2 hours. The methanol is removed by rotoevaporation, and the residue is purified to yield methyl 4-[4-(6-fluoro-2-quinoxalyloxy)phenoxy]-3-oxapentanoate.

nmr (CDCl₃) δ 1.30 (s, 1H, ##STR26## 2.20-3.20 (m, 7H, aromatic H), 5.25 (q, 1H, --OCHCH₃ C(O)--), 6.30 (s, 3H, OCH₃), 6.35 (s, 2H, --C(O)CH₂ C(O)--) and 8.45 ppn (d, 3H, --OCHCH₃ C(O)--).

EXAMPLE 34

Post-emergence herbicidal activity on the grasses (GR) green foxtail, watergrass, shattercane and wild oats and on the broadleafs (BL) annual morning glory, mustard, soybean and velvetleaf was tested for the compound of Example 31 and the compound of Example 32 (compounds No. 9 and 10) by spraying seedlings with a solution of water/acetone (1:1), surfactant (1%) and the test compound at a rate equivalent to 10 lb./acre. Scoring was made two weeks after spraying. The average herbicidal activity is given in percent control.

Pre-emergent herbicidal activity of the compounds No. 9 and 10 was tested on the above listed grasses and broadleafs (but with nightshade substituted for soybean) at a rate equivalent to 10 lb./acre. The average score is given in percent control.

    ______________________________________                                                     Pre         Post                                                   Compound No.  GR     BL         GR   BL                                        ______________________________________                                          9            100    0          100  20                                        10            100    0          100  57                                        ______________________________________                                    

EXAMPLE 35

A mixture of 2,3,5-trichloropyridine (2.5 g, 13.7 mm), hydroquinone (3.02 g, 27.4 mm), KOH (3.07 g, 54.8 mm) and DMSO (10 ml) is heated to 160° for 3 hours. The mixture is poured into water, acidified with dilute HCl and extracted with ether. The ethereal solution is washed, dried and evaporated to dryness. The crude product is chromatographed on silica gel to give crystalline 4-(3,5-dichloropyridyloxy)phenol.

The above phenol (1.3 g, 5.08 mm), K₂ CO₃ (1.05 g), methyl α-bromopropionate (0.85 ml, 1.5 eq) and acetone (20 ml) is refluxed for 8 hours. The mixture is then filtered and the filtrate concentrated to give oily methyl 2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionate.

The above propionate (1.9 g) in methanol (10 ml) is treated with 10% aqueous NaOH (10 ml) at RT for about 20 minutes. Most of the methanol is removed and the aqueous solution extracted with ether. The aqueous solution is acidified with dilute HCl and then extracted with ether. The combined extracts are dried and evaporated to give crystalline 2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionic acid.

The above acid is reacted with oxalylchloride to obtain the acid chloride which is converted to the meldrum acid and treated with ethanol following the procedure of Example 31 to yield ethyl 4-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]-3-oxopentanoate.

nmr (CDCl₃) δ 8.80 (t, 3H, OCH₂ CH₃), 8.50 (d, 3H, 7 Hz, OCH(CH₃)), 6.40 (s, 2H, --COCH₂ CO--), 5.84 (g, 2H, OCH₂ CH₃), 5.32 (q, 1H, OCH(CH₃)), 3.04 (m, 4H, --OC₆ H₄ O--), 2.34 (d, 1H, 2 Hz, pyridine H), 2.12 (d, 1H, 2 Hz, pyridine H).

In place of 2,3,5-trichloropyridine in the procedure of this Example, there is used 2,3-dichloro-5-trifluoromethylpyridine to yield as the final product, ethyl 4-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-oxopentanote.

EXAMPLE 36

Each of the 3-oxopentanoate products of Example 35 is reduced using NaBH₄ in ethanol to yield the 3-hydroxypentanote product. That is, ethyl 4-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-hydroxypentanoate and ethyl 4-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]-3-hydroxypentanoate.

nmr (CDCl₃) δ 8.76 (t, 3H, OCH₂ CH₃), 8.70 (d, 3H, 7 Hz, OCH(CH₃)), 7.43 (d, 2H, --CH₂ --CO--), 6.95 (t, 1H, --CH(OH)--), 5.84 (q, 2H, OCH₂ CH₃), 5.84 (m, 2H, OH, OCHCH₃), 3.04 (m, 4H, --OC₆ H₄ O--), 2.34 (d, 1H, 2 Hz, pyridine H), 2.12 (d, 1H, 2 Hz, pyridine H).

EXAMPLE 37

A mixture of 2,6,7-trichloroquinoxaline (0.8 q, 3.43 mm.), ethyl 4-(4-hydroxyphenoxy)-3-methoxy-2-pentenoate (1.09 g, 1.2 eq), K₂ CO₃ (568 mg) and CH₃ CN (20 ml) is refluxed overnight and then filtered. The filtrate is concentrated and taken up in CH₂ Cl₂. The CH₂ Cl₂ solution is washed, dried and evaporated to dryness to yield crystalline enol ether. Ethyl 4-[4-(6,7-dichloro-2-quinoxalyloxy)phenoxy]-3-methoxy-2-pentenoate.

The above enol ether (1.0 g), 35% HClO₄ (10 ml) and CH₂ Cl₂ (20 ml) is stirred at RT for 6 days followed by aqueous workup. The product is purified by prep. TLC (20% ethylacetate/hexane) to the 3-oxo ester. Ethyl 4-[4-(6,7-dichloro-2-quinoxalyloxy)phenoxy]-3-oxopentanoate.

nmr (CDCl₃) δ 8.80 (t, 3H, OCH₂ CH₃), 8.49 (d, 3H, 7 Hz, --OCHCH₃ CO--), 6.40 (s, 2H, --COCH₂ CO--), 5.92 (q, 2H, OCH₂ CH₃), 5.25 (q, 1H, --OCH(CH₃)CO--), 3.0 (q, 4H, --O--C₆ H₄ --O--), 2.27 (s, 1H, 1.99 (s, 1H), 1.44 (s, 1H, quinoxaline H).

The above 3-oxo ester is reduced using NaBH₄ in ethanol to yield ethyl 4-[4-(6,7-dichloro-2-quinoxalyloxy)phenoxy]-3-hydroxypentanoate.

Ethyl 4-(4-hydroxyphenoxy)-3-methoxy-2-pentenoate is prepared by the reaction hydroquinone and ethyl 4-bromo-3-methoxy-2-pentenoate in the presence of base in acetone or the like under reflux.

EXAMPLE 38

The procedure of Example 37 is repeated using 2,6-dichloroquinoxaline and methyl 4-(4-hydroxyphenoxy)-3-methoxy-2-pentenoate as the starting materials to yield methyl 4-[4-(6-chloro-2-quinoxalyloxy)phenoxy]-3-methoxy-2-pentenoate which is treated with 35% HClO₄ to yield the 3-oxo ester. Methyl 4-[4-(6-chloro-2-quinoxalyloxy)phenoxy]-3-oxopentanoate.

nmr (CDCl₃) δ 8.47 (d, 3H, 7 Hz, OCHCH₃), 6.37 (s, 2H, --COCH₂ CO--), 6.34 (s, 3H, OCH₃), 5.29 (q, 1H, OCHCH₃), 2.97 (q, 4H, --O--C₆ H₄ --O--), 2.40 (s, 2H), 2.0 (s, 1H), 1.34 (s, 1H, quinoxaline H).

The above 3-oxo ester is reduced using NaBH₄ in methanol to prepare the 3-hydroxy ester. Methyl 4-[4-(6-chloro-2-quinoxalyloxy)phenoxy]-3-hydroxypentanoate.

nmr (CDCl₃) δ 8.67 (d, 3H, --OCHCH₃ C--), 7.37 (d, 2H, --CH₂ --CO--), 6.79 (t, 1H, --CHOH--), 6.29 (s, 3H, OCH₃), 5.71 (m, 2H, --OCHCH₂ --, --CHOH), 1.35 (s, 1H, quinoxaline H).

EXAMPLE 39

To a solution of D(-)-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionic acid (500 mg, 1.52 mm) in ether (10 ml) and DMF (1 drop) is added oxalylchloride (0.8 ml, 2 eq). The mixture is stirred at RT for one hour and then concentrated to dryness to give the acyl chloride.

The acyl chloride in CH₂ Cl₂ (10 ml) is added at 0° to a solution of 240 mg of 2,2-dimethyl-1,3-dioxane-4,6-dione (IV) in CH₂ Cl₂ (10 ml) containing pyridine (0.2 ml). The mixture is stirred at 0° for one hour and then at RT for one hour. The mixture is taken up in CH₂ Cl₂, washed with dilute HCl and water, dried and evaporated to dryness to give 2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionyl meldrum's acid. The meldrum's acid is refluxed with ethanol for 6 hours. The mixture is then concentrated and purified by prep. TLC to give D(+) ethyl 4-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]-3-oxopentanoate. [α]₂₅ ^(D) =+11.58 in CHCl₃.

Examples of herbicides, in addition to the herbicides described hereinabove, which can be combined with a compound of the present invention in order to control a broad spectrum of weeds are described by W. T. Thomson, "Agricultural Chemicals--Book II Herbicides", Thomson Publications, Fresno, Calif., U.S.A., 1981-82 Revision, the entire disclosure of which is incorporated herein by reference.

EXAMPLE 40

To a solution of methyl 2-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]propionate (1.75 g) in methanol (15 ml) is added potassium hydroxide (1.0 g) in water (10 ml). The resulting mixture is stirred at RT until a clear solution is obtained (˜20 min). Most of the methanol is removed, and the aqueous solution is acidified with dilute HCl and extracted with ether. The combined ether extracts are dried and concentrated to dryness to give 2-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)-phenoxy]propionic acid.

To the above acid (2.1 g) in ether (20 ml) containing DMF (3 drops) is added, dropwise, oxalyl chloride (1 ml). The mixture is stirred at RT for 1 hour, then concentrated to dryness to give 2-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]propionic acid chloride.

The above acid chloride in methylene chloride (10 ml) is added, dropwise, at 0° to a solution of meldrum's acid (0.84 g) in methylene chloride (20 ml) containing pyridine (1 ml). After addition, the mixture is stirred at 0° for 1 hour, then at RT for 1.5 hour. It is then poured into water and extracted with methylene chloride. The combined extracts are washed with dil. HCl and with water, dried and evaporated to give an oily residue which is purified by prep. TLC to give ethyl 4-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-oxopentanoate.

nmr (CDCl₃) δ 8.80 (t, 3H, --OCH₂ CH₃), 8.49 (d, 3H, 7 Hz, --OCH(CH₃)), 6.40 (s, 2H, --COCH₂ CO--), 5.90 (q, 2H, --OCH₂ CH₃), 5.30 (q, 1H, --OCH(CH₃)), 3.03 (m, 4H, aromatic H), 2.09-1.80 (d, d, 2H, pyridine H).

EXAMPLE 41

Ethyl 4-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-oxopentanoate (680 mg) is reduced using NaBH₄ (60 mg) in ethanol (10 ml) to yield ethyl 4-[4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy]-3-hydroxypentanoate

nmr (CDCl₃) δ 8.70 (t, 3H, --OCH₂ CH₃), 8.67 (d, 3H, 7 Hz, --OCH(CH₃)), 7.29 (d, 2H, --CH₂ CO--), 5.84 (q, 2H, --OCH₂ CH₃), 5.84 (m, 1H, --OCH(CH₃)), 3.00 (m, 4H, aromatic H), 2.07 (d, 1H, 2 Hz, pyridine H), 1.80 (d, 1H, 2 Hz, pyridine H). 

What is claimed is:
 1. A compound of the formula: ##STR27## wherein X is hydrogen or chloro, Y is trifluoromethyl or chloro, and R₃ is lower alkyl.
 2. A compound according to claim 1, wherein Y is trifluoromethyl.
 3. A compound according to claim 1, wherein X and Y are chloro.
 4. A compound according to claim 3, wherein R₃ is ethyl.
 5. A compound according to claim 2 wherein X is hydrogen and R³ is methyl.
 6. A compound according to claim 2, wherein X is chloro and R³ is ethyl.
 7. A compound of the formula: ##STR28## wherein X is hydrogen or chloro, Y is trifluoromethyl or chloro, and R₃ is lower alkyl.
 8. A compound according to claim 7, wherein Y is trifluoromethyl.
 9. A compound according to claim 7, wherein X and Y are chloro.
 10. A compound according to claim 9, wherein R₃ is methyl.
 11. A compound according to claim 8, wherein X is chloro and R₃ is ethyl.
 12. A compound according to claim 9, wherein R₃ is ethyl.
 13. A compound according to claim 8, wherein X is hydrogen and R₃ is methyl.
 14. A compound according to claim 8, wherein X is hydrogen and R₃ is ethyl.
 15. A herbicidal composition which comprises a herbicidally effective amount of a compound of claim 1 in admixture with a suitable carrier material.
 16. A herbicidal composition which comprises a herbicidally effective amount of a compound of claim 5 in admixture with a suitable carrier material.
 17. A herbicidal composition which comprises a herbicidally effective amount of a compound of claim 6 in admixture with a suitable carrier material.
 18. A herbicidal composition which comprises a herbicidally effective amount of a compound of claim 7 in admixture with a suitable carrier material.
 19. A herbicidal composition which comprises a herbicidally effective amount of a compound of claim 11 in admixture with a suitable carrier material.
 20. A herbicidal composition which comprises a herbicidally efective amount of a compound of claim 13 in admixture with a suitable carrier material.
 21. A method for the control of weeds comprising an application of a herbicidally effective amount of a compound of claim 1 to the locus of said weeds.
 22. A method for the control of weeds comprising an application of a herbicidally effective amount of a compound of claim 5 to the locus of said weeds.
 23. A method for the control of weeds comprising an application of a herbicidally effective amount of a compound of claim 6 to the locus of said weeds.
 24. A method for the control of weeds comprising an application of a herbicidally effective amount of a compound of claim 8 to the locus of said weeds.
 25. A method for the control of weeds comprising an application of a herbicidally effective amount of a compound of claim 11 to the locus of said weeds.
 26. A method for the control of weeds comprising an application of a herbicidally effective amount of a compound of claim 13 to the locus of said weeds. 